This application proposes development of an integrated array of assays to quantitatively measure synaptic function in cultured neurons and acute brain slices, with the potential for scaling up these assays for high- throughput screens. As suggested by RFA-MH-11-40 Scalable Assays for Unbiased Analysis of Neurobiological Function, this grant does not address a specific biological question, but describes new tools for large-scale analysis of neuronal function. Specifically, our applications proposes in eight specific aims a series of related but independent new assay systems, including new methods of achieving controlled expression of neuronal genes in mice, and new techniques for measuring properties of synaptic function in neurons, ranging from pre- and postsynaptic calcium-signaling over analysis of glutamate receptor trafficking to imaging of neuronal excitation or silencing and various forms of neuronal stress. With these assays, our overall goal is to develop tools to meet the increasingly obvious need for better approaches to study neuro-psychiatric disorders such as autism and schizophrenia. A growing human genetics literature describes many candidate pathogenic genes for these disorders, with a synaptic function likely for some of the implicated genes such as neurexins, suggesting that synapses could represent a pathogenetic hotspot for at least a subset of cases in these diseases. Analyzing candidate disease genes, however, has proven difficult with current approaches that require long-term studies of single genes in time-consuming and expensive experiments. Thus, new approaches that can be scaled up and quantitated without enormous investments in time and effort are needed. The tools we describe here are meant to address this need, at least in part, and are based on a series of technical innovations. The tools can be applied to cultured neurons, acute slices, or in vivo experiments in mice, and primarily use optical detection methods as readout to allow scalability. All of the tools developed under the auspices of this application will be freely and immediately distributed to the community, with the hope that they will become standardized approaches for large-scale interrogation of synaptic function in projects performed throughout the country. This application attempts to address an urgent need for scalable assay systems for analysis of neuronal function, as enunciated by the RFA-MH-11-40. The proposed new assay systems focus on synaptic transmission because neuropharmacology and human genetics identified synaptic transmission as a possible site of impairment in many important brain diseases, including autism and schizophrenia.